A locator pin is a feature utilized to locate two components with respect to each other. As illustrated in FIGS. 1 and 2, a first component C1 includes the locator pin P while the second component C2 includes a tight clearance hole or aperture A that is aligned with and receives the locator pin when the two components are secured together. As illustrated, the prior art locator pin P includes two perpendicular ribs R that define a cross-shaped cross section.
One problem associated with the utilization of a cross-shaped locator pin P as illustrated in FIGS. 1 and 2 is that such a pin causes a sink mark M in the opposite side or A face (referenced herein as F) of component C1. See FIG. 3 illustrating the sink mark M. As should be appreciated, the sink mark M comprises a visible surface depression on the smooth surface F of a plastic component C1. This is due to the local thickening of the area at the intersection of the locator pin P, increasing the internal mass at that point. This increased internal mass retains heat during the injection molding process, maintaining the zone or area in a plastic state so that the material draws inward and contracts as cooling proceeds.
Various attempts have been made in the past to either eliminate or minimize the effect of such a sink mark M. For example, the smooth A surface or face F is sometimes textured in order to camouflage a sink mark. In another approach, the plastic part is thickened in the region around the locator pin P so that the thickness of the locator pin ribs R is substantially less than the thickness of the intersected section of the plastic component C1.
Although these methods have worked successfully in some applications, most of the time they have to be combined and, in some cases, combination is not enough to effectively eliminate a sink mark M. Further, there are also some cases in which it is impractical to modify the texture of the A surface, or the required thickening in the region around the locator pin P is too great and can lead to other problems. Thus, there exists a need to develop a new locator pin structure and/or a method to eliminate or reduce sink marks in plastic components incorporating a locator pin.
This document relates to a new and improved locator pin, a plastic component incorporating the locator pin, a plastic component assembly relying on the new and improved locator pin and a new and successful method to reduce sink marks in an injection molded plastic component including a locator pin.